1. Technical Field
The present invention relates generally to semiconductor manufacturing and related technologies. More particularly, the present invention relates to electron beam lithography systems and other electron beam based systems.
2. Description of the Background Art
As is well-understood in the art, a lithographic process includes the patterned exposure of a resist so that portions of the resist can be selectively removed to expose underlying areas for selective processing such as by etching, material deposition, implantation and the like. Traditional lithographic processes utilize electromagnetic energy in the form of ultraviolet light for selective exposure of the resist. As an alternative to electromagnetic energy (including x-rays), charged particle beams have been used for high resolution lithographic resist exposure. In particular, electron beams have been used since the low mass of electrons allows relatively accurate control of an electron beam at relatively low power and relatively high speed.
In general, electron beam lithographic systems may be designed to operate in either a reflection mode or a transmission mode. In a reflection mode, the electron beam is patterned by reflecting the beam from a selectively reflective array. If the pattern on the reflective array is dynamically changeable, then the array may be referred to as a dynamic pattern generator (DPG). In a transmission mode, the electron beam is patterned by transmitting the beam through a blanker array.
The electron-optical elements of electron beam lithographic systems generally cause imaging aberrations which need to be corrected. Aberration correction is typically performed using multi-pole elements. However, the multi-pole elements used for aberration correction are typically large and expensive and are limited as to which aberrations can be corrected.
It is highly desirable to improve lithography systems. The present disclosure provides advantageous apparatus and methods for correcting aberrations in an electron beam lithography system.